Digital broadcasting transmission/reception system utilizing srs and trs code to improve receiving performance and signal processing method thereof

ABSTRACT

A digital broadcasting transmission and/or reception system having an improved reception performance and a signal-processing method thereof. A digital broadcasting transmitter comprises a TRS encoder for to TRS-encode an MPEG-2 transmission stream having null data for inserting an SRS data and a TRS parity at predetermined positions, randomizer to input and randomize data stream from the TRS encoder, a SRS exchanger to replace the null data for inserting the SRS data to the known data, and an encoder for encoding a data streams to which the Known data is inserted. Accordingly, the present invention detects the known data from a signal received from a reception side and uses the detected known data for synchronization and equalization and further uses the TRS parity for correcting error of the received signal, so that the digital broadcasting reception performance can be improved at poor multipath channels.

TECHNICAL FIELD

The present invention relates to a digital broadcastingtransmission/reception system, and more specifically, to a digitalbroadcasting transmission/reception system transmitting predefined knowndata with a supplementary reference signal (SRS) added to an MovingPicture Experts Group-2 transport stream (MPEG-2 TS) to improveperformance of a reception system and utilizing a transversal ReedSolomon (TRS) code to reinforce error-correcting capacity and a signalprocessing method thereof.

BACKGROUND ART

The Advanced Television Systems Committee Vestigial Sideband (ATSC VSB)method, a U.S-oriented terrestrial waves digital broadcasting system, isa single carrier method and uses a field sync by 312 segment unit.Accordingly, reception performance is not good at poor channels,especially at a doppler fading channel.

FIG. 1 is a block diagram of a transmitter/receiver of a generalU.S-oriented terrestrial waves digital broadcasting system according tothe ATSC digital television (DTV) standards.

The digital broadcasting transmitter of FIG. 1 has a randomizer (110)for randomizing an MPEG-2 TS, an Reed-Solomon (RS) encoder (120) of aconcatenated coder form for adding a parity byte to the TS to correcterrors generated by channel characteristics on transmission, aninterleaver (130) for interleaving the RS encoded data in a certainpattern, and a ⅔ rate Trellis encoder (140) for performing ⅔ rateTrellis encoding and 8 level symbol mapping of the interleaved data, sothat error-correcting encoding of the MPEG-2 TS is performed.

Further, the digital broadcasting transmitter has a multiplexer (150)for inserting a field sync and segment sync in the error-correctingencoded data as a data format of FIG. 2, and a modulator (160) foradding a certain DigiCipher (DC) value to the data symbol inserted withthe segment sync and field sync, inserting a pilot tone therein,performing pulse-shaping and vestigial sideband (VSB) modulation,up-converting them into a signal of RF channel band and transmittingthem.

Accordingly, the digital broadcasting transmitter randomizes the MPEG-2TS through the randomizer (110), the randomized data are outer-codedthrough the RS encoder (120) which is an outer coder, and theouter-coded data are dispersed through the interleaver (130). Inaddition, the interleaved data are inner-coded by 12 symbol unit throughthe Trellis encoder (140) and the inner-coded data are mapped with a 8level symbol, inserted with the field sync and segment sync, insertedwith the pilot tone, VSB-modulated, up-converted into a RF signal andtransmitted.

Meanwhile, the digital broadcasting receiver of FIG. 1 has a tuner (notshown) for down-converting the RF signal received through a channel intoa basic signal, a de-modulator (210) for performing sync detection anddemodulation of the down-converted basic signal, an equalizer (220) forcompensating channel distortion which is generated by multipath in thedemodulated signal, a Viterbi decoder (230) for correcting errors in theequalized signal and decoding the signal in symbol data, a deinterleaver(240) for rearranging the data dispersed by the interleaver (130) of thedigital broadcasting transmitter, an RS decoder (250) for correctingerrors and a derandomizer (260) for derandomizing the data correctedthrough the RS decoder (250) and outputting the MFEG-2 TS.

Accordingly, the digital broadcasting receiver of FIG. 1 down-convertsthe RF signal into baseband, demodulates and equalizes thedown-converted signal, performs channel decoding, and restores theoriginal signal in a reverse order of the digital broadcastingtransmitter.

FIG. 2 shows a vestigial sideband (VSB) data frame of the U.S-orienteddigital broadcasting (8-VSB) system which is inserted with the segmentsync and field sync. As shown in FIG. 2, one frame consists of twofields and one field consists of one field sync segment which is thefirst segment and 312 data segments. Further, one segment of VSB dataframe corresponds to one MPEG-2 packet and consists of a segment sync offour symbols and 828 data symbols.

In FIG. 2, the segment sync and field sync are used for synchronizationand equalization in the digital broadcasting receiver. That is, thesegment sync and field sync are already known data between the digitalbroadcasting transmitter and receiver and are used as a reference signalon equalization of the receiver.

The VSB method of the U.S-oriented terrestrial waves digitalbroadcasting system as shown in FIG. 1 is a single carrier method and isweak in a multipath fading channel environment. Accordingly, performanceof a receiver depends on performance of an equalizer to removemultipath.

However, according to the conventional transmission frame as shown inFIG. 2, as a field sync which is a reference signal of the equalizerappears every 313 segment, the frequency of the field sync is lowcompared with a signal of one frame so that equalization performancedecreases.

In other words, it is not easy to estimate a channel, remove multipath,and equalize a received signal using the conventional equalizer and theabove mentioned known data of small quantity. Accordingly, theconventional digital broadcasting receiver has low reception performancein a poor channel environment, especially, in the Doppler fading channelenvironment.

Additionally, the VSB method of the U.S-oriented terrestrial wavesdigital television system of FIG. 1 is a single carrier system and hasthe low capacity to remove multipath in the Doppler multipath fadingchannel. However, if the known sequence such as a field sync is used alot, the channel is easily estimated and the equalizer easilycompensated the signal distorted by multipath using the known sequence.

However, as shown in the VSB data frame of the U.S-oriented terrestrialwaves digital television system of FIG. 2, a field sync which is knowndata appears every 313 segment. This is so small quantity, so that thecapacity to remove the multipath by using this decreases. Especially,the capacity to remove multipath in the Doppler multipath fadingchannels is low.

DISCLOSURE OF INVENTION Technical Problem

An aspect of the present invention is to provide a digital broadcastingtransmitter/receiver which insert null data without information atcertain intervals in an MPEG-2 packet to improve reception performanceof the U.S-oriented terrestrial waves digital television system of theVSB method, transmit SRS and add TRS code so that the receiver detectsand uses the SRS, and more efficiently corrects errors by the TRS codeto improve reception performance and a signal processing method thereof.

Technical Solution

To achieve the aspect of the present invention, a digital broadcastingtransmitter includes a TRS encoder for receiving an MPEG-2 TS andperforming TRS encoding of the MPEG-2 TS, the MPEG-2 TS including nulldata to insert SRS data and TRS parity respectively at a certainlocation, a randomizer for randomizing the data output from the TRSencoder, an SRS replacing part for replacing the null data to insert SRSdata of the randomized data with the SRS data, an RS encoder forRS-encoding the data output from the SRS replacing part and adding an RSparity, an interleaver for interleaving the data output from the RSencoder, a Trellis encoder for Trellis-encoding the data output from theinterleaver and a modulator for modulating the data output from theTrellis encoder, performing RF converting and transmitting the resultantdata.

Preferably, the null data to insert the SRS data are constructed to acertain amount at the certain location of each segment.

More preferably, the data stream has the information on the insertionlocation and the amount of the null data, and the information isinserted prior to the location where the null data are inserted.

Further, the digital broadcasting transmitter further includes a controlsignal generator for generating a control signal to control the SRSreplacing part to insert the SRS data at the location according to theinformation.

Moreover, the Trellis encoder has a memory element for Trellis encodingoperation, initializes the memory element at the location where the SRSdata are inserted and performs Trellis encoding.

Further, the digital broadcasting transmitter further includes a packetbuffer for receiving and storing the data which are output from the RSencoder and which correspond to the location where the memory element ofthe Trellis encoder is initialized.

More preferably, the packet buffer receives the data altered accordingto the initialization of the memory element from the Trellis encoder.

Further, the digital broadcasting transmitter further includes a parityreplacing part for RS-encoding the altered data, which are input fromthe packet buffer, according to the initialization of the memoryelement, generating and outputting an altered RS parity to the Trellisencoder, so that the RS parity added by the RS encoder is replaced bythe altered RS parity.

Preferably, the TRS encoder includes a buffer for storing data input inthe row direction and outputting the data in the column direction, anencoder for TRS encoding the data output from the buffer and adding theTRS parity in the column direction, and a memory for receiving andstoring the data added with the TRS parity and outputting the data inthe row direction.

Furthermore, a signal processing method for a digital broadcastingtransmitter according to the present invention includes a TRS encodingstep of receiving an MPEG-2 TS and performing TRS encoding of the MPEG-2TS, the MPEG-2 TS including null data to insert SRS data and TRS parityrespectively at a certain location, a randomizing step of randomizingthe data output from the TRS encoding step, an SRS replacing step ofreplacing the null data, of the randomized data to insert SRS data withthe SRS data, an RS encoding step of RS-encoding the data output fromthe SRS replacing step and adding RS parity, a interleaving step ofinterleaving the data output from the RS encoding step, a Trellisencoding step of Trellis-encoding the data output from the interleavingstep and a step of modulating the data output from the Trellis encodingstep, performing RF converting and transmitting the resultant data.

A digital broadcasting receiver corresponding to the digitalbroadcasting transmitter according to the present invention includes ademodulator for receiving a signal from the digital broadcastingtransmitter and demodulating the received signal, the signal beinginserted with SRS and TRS parity at a certain location, a known dataoutput part for detecting the location of the SRS from the demodulatedsignal and outputting the SRS, a equalizer for equalizing thedemodulated signal, a Viterbi decoder for error-correcting and decodingthe equalized signal using the output SRS, a deinterleaver fordeinterleaving the data output from the Viterbi decoder, a derandomizerfor derandomizing the data output from the deinterleaver, and a TRSdecoder for TRS-decoding the data output from the derandomizer using theTRS parity.

Preferably, the known data output part includes a known data detectorfor detecting the information on the certain location and an amount ofthe inserted SRS from the received signal, a segment flag generator forgenerating a data frame including at least one segment which indicatesthe location with a predetermined flag, a Trellis interleaver forencoding the data frame as encoded in the digital broadcastingtransmitter, and a known data extractor for extracting and outputtingthe SRS at the location marked with the flag of the encoded data frame.

Further, the TRS decoder includes a buffer for storing data input in therow direction and outputting the data in the column direction, a decoderfor TRS-decoding the data output from the buffer using the TRS parity,and a memory for receiving and storing the TRS-decoded data andoutputting the data in the row direction.

In addition, a signal processing method for a digital broadcastingreceiver according to the present invention includes a step of receivinga signal from the digital broadcasting transmitter and demodulating thereceived signal, the signal being inserted with SRS and TRS parity at acertain location, a step of detecting the location of the SRS from thedemodulated signal and outputting the SRS, a step of equalizing thedemodulated signal, a step of error-correcting and decoding theequalized signal using the output SRS, a step of deinterleaving thedecoded data, a step of derandomizing the deinterleaved data and a stepof TRS-decoding the derandomized data using the TRS parity.

ADVANTAGEOUS EFFECTS

According to the present invention, to improve reception performance ofthe ATSC VSB system of the U.S-oriented terrestrial waves digitaltelevision system, an MPEG-2 packet is inserted with null data atcertain intervals, transmitted in SRS, and added with TRS code so thatreception performance is improved and reception range can be extendeddue to low required Signal to Noise Ratio (SNR). Additionally, there iscompatibility with the conventional system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a general digital broadcasting (ATSC VSB)transmitter/receiver,

FIG. 2 is a view showing a frame structure of ATSC VSB data,

FIG. 3 is a block diagram of a digital broadcasting transmitter/receiveraccording to the present invention,

FIG. 4 is a view showing a format of TRS input data added with null dataaccording to the present invention,

FIG. 5 is a view showing a format of the data output from a TRS encoder,

FIG. 6 is a view showing a format of data output from a parity replacingpart,

FIG. 7 is a view showing a format of data output from a datainterleaver,

FIG. 8 is a detailed block diagram of a TRS encoder and decoder, and

FIG. 9 is a block diagram of a known data output part.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention is described in detail referring toaccompanying drawings.

FIG. 3 is a block diagram of a digital broadcasting transmitter/receiveraccording to the present invention.

In FIG. 3, a TS, which is input to the digital broadcasting transmitter,is inserted with null data to generate a SRS, which is predefined knowndata between the transmitter and the receiver, and a TRS code parity.This will be described in detail later.

The digital broadcasting transmitter includes a TRS encoder (300) foradding RS parity in the column direction, a randomizer (310) forrandomizing the data, a SRS replacing part (315) for replacing null dataof the randomized data with a SRS, an RS encoder (320) for adding a RSparity in the row direction, a packet buffer (325) for storing the RSencoded SRS in memory initialization of a Trellis encoder (340) andreplacing it with a altered value according to initialization, a parityreplacing part (335) for RS encoding again using the altered value,generating a parity, and inputting the generated parity to the Trellisencoder (340), an interleaver (330) for interleaving the RS encodeddata, the Trellis encoder (340) for converting the interleaved data intosymbol and performing ⅔ rate Trellis encoding and symbol mapping, amultiplexer (350) for inserting a field sync and segment sync as a dataformat of FIG. 2, and a modulator (360) for inserting a pilot,performing VSB modulation, RF converting and transmitting the data.Additionally, the digital broadcasting transmitter further includes acontrol signal generator (370) for generating a operation control signalto process the null data according to the location and quantity of thenull data.

FIG. 4 shows a data format of an MPEG-2 TS input to a digitalbroadcasting transmitter according to the present invention.

Referring to FIG. 4, one field of the MPEG-2 TS according to the presentinvention consists of 312 segments with a header having a sync of thefirst byte and packet identity (PID) of the next three bytes, ‘m’ bytesafter the header consists of null data to insert a SRS, and a part afterthe null data consists of payload data. However, certain segments, whichare the part for the payload data, at the bottom of a field consists ofnull data to insert TRS.

The TRS encoder (300) performs RS encoding of the MPEG-2 TS input to thedigital broadcasting transmitter in the column direction and adds RSparity, which is generated in the column direction, at the location ofnull data inserted in the input TS to generate TRS parity.

FIG. 5 shows a format of the data output from the TRS encoder (300).Referring to FIG. 5, TRS parity generated by the TRS encoder (300) isadded to the location where the null data for TRS are inserted in thedata format of FIG. 4.

The randomizer (310) randomizes the input MPEG-2 TS data to increaseapplication of the allocated channel space.

The SRS replacing part (315) generates particular sequence data of acertain pattern which are predefined between the transmitter and thereceiver as a SRS, replaces the randomized data at the location of thenull data for SRS in the randomized data by inserting the particularsequence data therein. The pattern of the SRS is different from that oftransmitted/received payload data and the SRS is easily detected fromthe payload data to transmit so that the SRS is utilized forsynchronization and equalization of the receiver.

The RS encoder (320) RS encodes the packet data to correct errors by achannel and adds parity of certain bytes.

The interleaver (330) interleaves the parity-added packet output fromthe RS encoder (320) in a certain pattern.

The Trellis encoder (340) converts the data output from the interleaver(330) into symbols and performs symbol mapping through ⅔ rate Trellisencoding. The Trellis encoder (340) initializes a value which istemporarily stored in its own memory element at the beginning locationof the SRS and Trellis-encodes the known data.

The packet buffer (325) outputs and temporarily stores the data from thebeginning location of the data corresponding to the location of the SRSfrom the packet output from the RS encoder (320). Then, when the dataare altered according to the initialization of the Trellis encoder(340), the packet buffer (325) receives a certain amount of the altereddata from the Trellis encoder (340), replaces the previous data whichare temporarily stored, by temporarily storing the altered data, andinputs the altered data to the parity replacing part (335) to regenerateRS parity.

The parity replacing part (335) receives the data altered according tothe memory initialization, regenerates an RS parity according to thealtered data, and inputs it to the Trellis encoder (340) so that theprevious parity is replaced with the regenerated parity.

FIG. 6 shows a format of the data output from the parity replacing part(335). Referring to FIG. 6, the data altered according to theinitialization of the Trellis encoder (340) of the SRS data which havebeen replaced by the SRS replacing part (315) are RS-encoded so that anew RS parity is generated and replaces the previous RS parity.

Therefore, the packet data output from the Trellis encoder (340) to themultiplexer (350) has a format of the data, which is altered accordingto the memory element initialization of the Trellis encoder (340), andadded with the RS parity according to subsequent RS encoding.

FIG. 7 shows a format of the data output from the interleaver (330), andindicates the location of data for the SRS and the location of the RSparity.

Referring to FIG. 7, the corresponding RS parity is located after thedata for SRS. Accordingly, when the Trellis encoder (340) sequentiallyencodes the data input from the interleaver (330) and finishes dataencoding for SRS, the parity for this is replaced with the alteredparity output from the parity replacing part (335) and encoded so thatencoding is sequentially performed.

As shown in the data format which is converted into symbols by theTrellis encoder (340) of FIG. 2, the multiplexer (350) inserts a segmentsync in segment unit and a field sync in field unit, adds a certain DCvalue to a data signal of a certain level and inserts a pilot signal inedge part of low frequency band on frequency spectrum.

The modulator (360) performs pulse shaping of the signal which isinserted with the pilot signal, loads it on intermediate frequencycarrier wave and modulates amplitude for VSB modulation. Then, themodulated signal is converted into RF, amplified and transmitted througha channel allocated in a certain band.

The control signal generator (370) receives the null data-added TS fromthe randomizer (310), detects the information from the TS regarding thelocation where the null data are added, generates a control signal torecognize the beginning location and ending location, and inputs thecontrol signal to the SRS replacing part (315), the interleaver (320)and the Trellis encoder (340).

Meanwhile, the digital broadcasting receiver according to the presentinvention operates in a reverse order of the transmitter and includes ademodulator (410) for lowering the RF signal to baseband anddemodulating the RF signal, an equalizer (420) for deleting inter-symbolinterference, a Viterbi decoder (430) for error-correcting and decoding,a deinterleaver (440), an RS decoder (450), a derandomizer (460), a TRSdecoder (470) and a known data output part (480) for detecting andoutputting the location of the known data.

The demodulator (410) detects synchronization according to the pilotsignal and sync inserted in the baseband signal of the received signaland performs demodulation. In addition, the equalizer (420) compensatesmultipath channel distortion of the demodulated signal and removes thereceived inter-symbol interference.

The Viterbi decoder (430) corrects errors, decodes the error-correctedsymbol and outputs the symbol data. The decoded data rearranges thedispersed data through the deinterleaver (440).

The deinterleaved data are error-corrected through the RS decoder (450)and the error-corrected data are derandomized through the derandomizer(460).

The TRS decoder (470) corrects errors using the RS parity which is addedin the column direction so that the data of MPEG-2 TS are restored.

FIG. 8 shows a detailed block diagram of the TRS encoder (300) and TRSdecoder (470) according to the present invention.

The TRS encoder (300) includes a buffer (301) for storing the data inputin the row direction and outputting the data in the column direction, anencoder (303) for TRS-encoding the data input in the column directionfrom the buffer and adding parity in the column direction, and a memory(305) for receiving and storing the parity-added data in the columndirection and outputting the data in the row direction.

Additionally, the TRS decoder (470) has a buffer (471) for storing thedata input in the row direction and outputting the data in the columndirection, a decoder (473) for error-correcting the data input in thecolumn direction from the buffer (471) using the RS parity which isadded in the column direction, and a memory (475) for storing theerror-corrected data and outputting the data in the row direction.

Meanwhile, the known data output part (480) detects the information onthe location of the known data from the demodulated data, generatessegment frame, performs encoding and outputs the generated known data,and provides them for synchronization detection of the demodulator (410)and channel distortion compensation of the equalizer (420).

FIG. 9 shows a detailed block diagram of the known data output part(480).

Referring to FIG. 9, the known data output part (480) includes a knowndata detector (481), a segment flag generator (483), a Trellisinterleaver (485), and a known data extractor (487).

The known data detector (481) detects the quantity information of nullpacket inserted in the reserved part of field sync data segment sectionof the demodulated data and acquires the information on the location andlength of the known data.

According to the detected information on the quantity of the nullpacket, that is, according to the information on the location and lengthof the known data, the segment flag generator (483) marks with apredetermined flag of length corresponding to the number of data symbolsat the corresponding location and generates at least one segment and anMPEG-2 transmission frame including the segment.

The Trellis interleaver (485) encodes the transmission frame generatedin the segment flag generator (483) as the encoding of the transmitter,and detects the known data according to the flag.

Therefore, the known data extractor (487) acquires the information onthe location which is detected by the flag of the transmission frameswhich are encoded and output from the Trellis interleaver (485), andextracts and outputs the known data at the corresponding location.

According to the present invention, in order to improve receptionperformance of VSB method of the U.S-oriented terrestrial waves digitaltelevision system, a null packet without information are inserted atcertain intervals in an MPEG-2 packet, known symbol data are transmittedfrom the transmitter using them, and a TRS code is added, and thereceiver detects and uses the known symbol data, and re-performserror-correcting using the TRS codes so that reception performance canbe improved at poor multipath channels.

Moreover, SNR to satisfy TOV can be lowered using TRS codes. Thisproposed method guarantees compatibility with the existing receiverssuggested by ATSC, and system performance can be improved withoutperformance degradation of the existing receivers.

Accordingly, reception performance of ATSC VSB method of theU.S-oriented terrestrial waves digital television system can be enhancedaccording to the present invention.

1. A digital broadcast receiver, comprising: a demodulator to receive atransport stream, and demodulate the received transport stream; anequalizer to equalize the demodulated transport stream; a known dataoutput unit to detect known data from the transport stream, and provideat least one of the demodulator and the equalizer with the detectedknown data; and a TRS decoder to perform TRS decoding on the transportstream, wherein the transport stream is broadcasted from a digitalbroadcast transmitter comprising a Trellis encoder to reset a memory inorder to handle the known data and a parity replacing unit to compensatea parity to correspond to the resetting.
 2. The digital broadcastreceiver of claim 1, wherein the TRS decoder corrects errors using aReed-Solomon (RS) parity which is added to the transport stream in acolumn direction.
 3. The digital broadcast receiver of claim 1, whereinthe TRS decoder comprises: a buffer to store data input in a rowdirection, and output the stored data in a column direction; a decoderto correct errors on the data output in a column direction using the RSparity added in a column direction; and a memory to store the correcteddata, and output the stored data in a row direction.
 4. The digitalbroadcast receiver of claim 1, wherein the known data output unitdetects information regarding known data from the transport streamdemodulated by the demodulator, and detects the known data according tothe detected information.
 5. The digital broadcast receiver of claim 1,wherein the known data output unit comprises: a known data detector todetect information regarding known data from the transport streamdemodulated by the demodulator; a segment flag generator to generate asegment by indicating an identification according to the detectedinformation, and generate a transport frame having the generatedsegment; a Trellis interleaver to encode the generated transport frameto correspond to the digital broadcast transmitter; and a known dataextractor to extract known data from the transport frame output from theTrellis interleaver according to the identification.
 6. A method forprocessing a stream of a digital broadcast receiver, the methodcomprising: receiving a transport stream, and demodulating the receivedtransport stream; equalizing the demodulated transport stream; detectingknown data from the transport stream; and performing TRS decoding on thetransport stream, wherein at least one step of the demodulating andequalizing uses the detected known data, and wherein the transportstream is broadcasted from a digital broadcast transmitter comprising aTrellis encoder to reset a memory in order to handle the known data anda parity replacing unit to compensate a parity to correspond to theresetting.
 7. The method of claim 6, wherein the performing TRS decodingcomprises: correcting errors using a Reed-Solomon (RS) parity which isadded to the transport stream in a column direction.
 8. The method ofclaim 6, wherein the performing TRS decoding comprises: buffering datainput in a row direction, and outputting the stored data in a columndirection; correcting errors on the data output in a column directionusing the RS parity added in a column direction; and outputting thecorrected data in a row direction.
 9. The method of claim 6, wherein thedetecting comprises: detecting information regarding known data from thedemodulated transport stream, and detecting the known data according tothe detected information.
 10. The method of claim 6, wherein thedetecting comprises: detecting information regarding known data from thedemodulated transport stream; generating a segment by indicating anidentification according to the detected information, and generating atransport frame having the generated segment; encoding the generatedtransport frame to correspond to a digital broadcast transmitter; andextracting known data from the encoded transport frame according to theidentification.